Truck bed toolbox lid method of manufacture

ABSTRACT

An improved truck bed toolbox lid and a method of producing the same. The truck bed toolbox lid includes an outer metallic sheet layer comprising a generally rectangular top sheet member, a longitudinal front edge member, two lateral edge members and a longitudinal rear edge member. A metallic liner sheet member is disposed inside the top sheet member in edge contact abutment with beveled inside edges of the front and rear longitudinal edge members and the lateral edge members to create an internal cavity in which the liner is by stitch welding. One or more injection ports are provided through the liner sheet member through which a self-expanding and self-curing, relatively high-density, foam is injected. The stitch welded edge contacts leave non-welded, gas permeable junctions along the wedged cavity periphery at a funneled apex of the edge contacted boundary which facilitate expansion of the foam toward the outermost edges of the cavity.

This application is a divisional of U.S. patent application Ser. No.10/300,968, filed Nov. 20, 2002, now abandoned, which is acontinuation-in-part of U.S. patent application Ser. No. 09/779,228,filed Feb. 8, 2001 now abandoned, which claims the benefit of U.S.Provisional Application Ser. No. 60/181,858, filed Feb. 11, 2000.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to the field of truck bedtoolboxes. More particularly, the present invention relates to animproved truck bed toolbox and toolbox lid combination that isstructurally improved to better withstand the bending and twistingforces experienced by such toolboxes as disposed and utilized in thebeds of pick-up trucks, and the method of manufacturing such truck bedtoolbox lid.

2. Description of the Related Art

A truck bed toolbox is a well known pick-up truck accessory which isessentially a storage cabinet designed for outdoor exposure and having adistinctive outer contour and dimensions suitable for being fixedlymounted in the open bed of a pick-up truck, generally just to the rearof the passenger compartment. Such a toolbox typically comprises agenerally rectangular, open topped lower receptacle or tub, to which ispivotally attached one or more lid members. A single lid is typicallyattached by hinges affixed along the longitudinal rear edge of the lidand the back wall of the tub if a single lid, or a pair of lids areaffixed by hinges affixed transversely adjacent the lateral middle ofthe tub. Closure means, latches, locks or the like are provided tosecure the lid or lids in the closed positioned. The box may be providedwith lift cylinders and detent means to maintain the lid in the openposition, or other features. Such devices are well known, and typifiedin being constructed of metallic sheet members suitable foraccommodating large, heavy metallic tools.

The truck bed box/lid combination are typically constructed ofrelatively rigid, aluminum sheet material having requisite strength andcorrosion resistance characteristics. The individual aluminum panels ofa truck bed toolbox typically have a thicknesses of from 0.080 to 0.063mil, and are welded or mechanically fastened to define the sheet metalbox structure characteristic of truck bed tool boxes. Since they mustspan the width of a truck bed compartment, these specialized toolboxesare relatively large typically ranging from 54 to 75 inches in width,from 19 to 28 inches in depth and from 13 to 14 inches in height. Thedisproportionate width (i.e. 54 to 75 inches) is a distinctcharacteristic of truck bed toolboxes for helping to maintain thetoolbox anchored in relative abutment with the interior sidewalls of thetruck bed such that the toolbox remains within a designated crosssection area of the truck bed while experiencing shifting forcesresulting from the truck's motion while being driven. Thedisproportionate width dimension is also useful for truck bedapplications by rendering the lid accessible to a user standing on theside of the host truck's bed and reaching over the bed sidewall to openthe toolbox.

Because the lid is the main movable component of the toolbox, it issubjected to repetitive forces from many directions and is therefore thecomponent most susceptible to damage or failure. Due to the relativelylarge width dimension necessitated by the reasons set forth above andits flat, metallic sheet construction, a truck bed tool box lid isparticularly susceptible to twisting and bending forces resulting fromusers opening the toolbox by pushing up on or near an outer end of thelid accessible while standing outside the truck bed. If the lid becomestwisted or otherwise misaligned, proper closure to seal the box from theelements becomes difficult or impossible, and the toolbox must then berepaired or replaced. It is therefore necessary to impart significantrigidity to prevent the lid from bending, crimping, torqueing, twisting,failing or becoming misaligned relative to the tub. It is standardpractice to fasten structural bracing members on the underside of thelid to increase planar rigidity, the bracing members extending eitherlongitudinally or laterally, but the efficacy of these brace members islimited by the desire to minimize cost and weight factors, such thatmanufacturers attempt to use the smallest or the fewest brace memberswhich will still provide a minimally acceptable increase in rigidity andstructural integrity.

Another method for increasing the rigidity and structural integrity ofthe lid is to provide an interior liner sheet to form a cavity intowhich pre-cured, cut-to-size, rigid foam sheets are inserted. However,in order to achieve the desired load transfer across the componentmaterials necessary to resist shearing and buckling forces requires thatadhesive agents be applied to the contact surfaces which greatlyincreases the time and cost of production of each truck bed toolbox lid.Furthermore, employing pre-formed foam sheets results in cutting thefoam sheets to size resulting in significant waste of materials and inenvironmental hazards in disposing of the same.

It can therefore be appreciated that a need exists for an improved truckbed toolbox lid and method of producing the same, wherein the truck bedtoolbox lid is lighter and less susceptible to misalignment.

SUMMARY OF THE INVENTION

An improved truck bed toolbox, an improved truck bed toolbox lid, and amethod of producing the same are disclosed herein. The truck bed toolboxlid includes a metallic liner bounded cavity filled with high densityinjected foam to provide superior strength and rigidity, to maintain thelid alignment and to virtually eliminate the need to adjust lidstrikers. In accordance with the present invention, the lid comprises anouter layer of aluminum or similar sheet material, the outer layercomprising a generally rectangular top sheet member, a longitudinalfront edge member, two lateral edge members and a longitudinal rear edgemember, where the edge members depend from the metallic top sheet memberand overlap the upper edges of the truck bed toolbox rectangular tub orbase. A liner sheet member of aluminum or other suitable metal ispositioned to the inside of and substantially parallel to the metallictop sheet member. The liner sheet member is spaced a short distance fromthe top sheet member to create an internal cavity in which the liner isdisposed in edge contact abutment with beveled inside edges of the frontand rear longitudinal edge members and the lateral edge members bystitch welding. One or more injection ports are provided through theliner sheet member through which a self-expanding and self-curing,relatively high-density, foam is injected to completely fill theinterior cavity. The stitch welded edge contacts leave non-sealed, gaspermeable junctions along the wedged cavity periphery at the funneledapex of the edge contacted boundary which facilitate expansion of thefoam toward the outermost edges of the cavity to maximize the foamcoverage at points furthest from the foam injection site. The cured,expanded foam adheres to the inside surfaces of the metallic top sheetmember and the inside surface of the metallic liner sheet member,creating a rigid composite structure whereby shearing and twistingforces are more evenly distributed through the composite structure, suchthat the lid is able to withstand much greater detrimental forceswithout permanent flexing, bending, crimping or failure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a truck bed toolbox according tothe present invention with the lid in the closed position attached tothe tub.

FIG. 2 is a cross-sectional view of a truck bed toolbox lid inaccordance with one embodiment of the present invention.

FIG. 3 is a bottom view of a truck bed toolbox lid in accordance withone embodiment of the present invention.

FIG. 4 is a bottom view of a truck bed toolbox lid in accordance with analternate embodiment of the present invention.

FIG. 5 depicts an apparatus for preparing and assembling a truck bedtoolbox lid in accordance with a preferred embodiment of the presentinvention.

FIG. 6 is a flow diagram illustrating steps performed during productionof a truck bed toolbox lid in accordance with a preferred embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, the invention will now be described indetail with regard for the best mode and the preferred embodiment.

As explained in further detail with reference to the figures, thepresent invention is directed to an improved truck bed toolbox lidhaving greater rigidity and resistance to bending and twisting thanstandard constructions, where the improved lid is relatively easy tomanufacture at lower costs. The improved internal support is provided byan improved injected foam process and results in a highly resilienttruck bed toolbox lid having optimum rigidity characteristics such thatthe thickness of the lid shell material may be reduced (from 0.080 milto 0.063 mil, for example) while increasing the flexural integrity ofthe lid. Furthermore, the improved truck bed toolbox lid assembly methoddescribed herein provides a more efficient assembly line processresulting in less man-hours per toolbox assembly and a correspondingincrease in the rate of production.

With reference now to the figures wherein like reference numerals referto like and corresponding parts throughout, and in particular withreference to FIG. 1, there is depicted a perspective view showing atruck bed toolbox according to the present invention with the lid in theclosed position attached to the tub. In particular, FIG. 1 illustratesthe apparatus of the present invention as generally comprising astructurally superior truck bed toolbox lid 20 for a truck bed toolbox10 of the type configured to be positioned in the bed of the open cargoarea of a pick-up truck, usually abutting the rear of the cab andextending laterally across the bed. The box 10 typically includes agenerally rectangular tub or base member 15 having upstanding side walls11 with upper edges 12. The box 10 is provided with latching or lockingmeans 13 to secure the lid 20 in the closed position, and the lid 20 ispivotally joined to the tub 15 by hinge means 14. The major structuralcomponents are preferably composed of sheet metal, such as aluminum. Inthe depicted embodiment, the box 10 is shown as comprising a single lid20, but it is to be understood that the structure as described herein isapplicable to truck bed toolboxes having pairs of lid members, in whichcase the lid members are pivotally joined to the tub along a lateraledge, preferably an interior lateral edge with the hinges mountedtransversely.

Preferably, the tub 15 is produced by cutting and folding an aluminumsheet to create the front, bottom and back walls with the side wallswelded to create the full base structure. Likewise, the outer panels ofthe lid 20 are preferably formed by cutting and folding a singlealuminum sheet to form the top sheet member 21, front edge member 22,lateral edge members 23 and rear edge member 24.

Referring to FIG. 2 in conjunction with FIG. 1, the truck bed toolboxlid 20 comprises a generally planar top or outer sheet member 21 fromwhich depend a longitudinal front edge member 22, a pair of opposinglateral edge members 23 and a rear edge member 24, where one or morehinge means 14 are connected in some manner to the rear edge member 24such that the lid 20 can be pivoted preferably at least 90 degrees fromthe tub 15 in the open position. Lift cylinders or detent means, notshown but known in the art, may be provided to retain the lid 20 in theopen position. The edge members 22, 23 and 24 form a complete perimeteraround the metallic top sheet member 21, which is sized to allow theedge members 22, 23 and 24 to overlap the upper edges 12 of the tubwalls 11 to preclude entry of rain, dirt and other detrimentalenvironmental effects. As depicted in FIGS. 1 and 2, edge members 22, 23and 24 are preferably partially beveled between the top horizontalsurface of top sheet member 21 and the vertically depending portion ofthe edge members. Furthermore, all or some of edge members 22, 23 and 24may be provided with a hem 25, which is formed by bending the outerportion of the edge member 22, 23 or 24 back upon itself such that arounded configuration is presented in areas where the user may contactthe edge members 22, 23 and 24.

The truck bed toolbox lid 20 further comprises a metallic liner sheetmember 30, preferably formed of a sheet metal such as aluminum, which ismounted on the inside of the metallic top sheet member 21. The metallicliner sheet member 30 is preferably planar and substantially coextensiveand parallel with the metallic top sheet member 21 in the horizontaldirection, but is separated from the metallic top sheet member 21 ashort distance to define an interior cavity 42. As depicted in FIG. 2,the metallic liner sheet member 30 is preferably disposed at its edges31 in substantially continuous abutment along the inside beveledsurfaces of edge members 22, 23 and 24. The edges 31 of the liner sheetmember 30 are fixedly connected to the edge members 22, 23 and 24 bymultiple, individual stitch or spot welds 99 preferably having a widthfrom 0.5″ to 1.5″ and being spaced apart by 2″ to 6″ along the perimeterof metallic liner sheet member 30. In accordance with a preferredembodiment, the liner edges 31 are hemmed or otherwise bent ormanipulated to provide a suitably enlargened weld surface on liner edges31 and furthermore to provide a suitably dimensioned “well” in which aheat-activated adhesive can be deposited after stitch welding.Preferably the stitch welds 99 extend for short distances of one inch orless, as this technique minimizes damage to the aluminum sheets from theheat of welding. Moreover, utilization of discrete weld joints in thismanner provides a particularly well-suited forum for implementing a foaminjection technique explained in further detail with reference to FIG.3. In alternative embodiments, suitable means such as mechanicalfasteners may be utilized for applying discrete suitably spacedattachment joints to affix the metallic liner sheet member 30 to themetallic top sheet member 21.

With reference to FIG. 3, there is illustrated a bottom view of a truckbed toolbox lid in accordance with one embodiment of the presentinvention. Specifically, FIG. 3 depicts the underside of the lid 20wherein the rectangular periphery of liner sheet member 30 is situatedin edge contact within a continuous, beveled edge perimeter 33 formedalong the depending front, rear and lateral edge members on theunderside cavity of the top sheet member 21. The metallic liner sheetmember 30 is provided with one or more injection ports or apertures 41,which allow a self-expanding, self-curing foam material 40 to beinjected into the interior cavity 42, where it self-bonds and adhereswithout need for application of a separate adhesive material to theinside of the metallic top sheet member 21, the metallic liner sheetmember 30 and the edge members 22, 23 and 24, depending on theconfiguration of the metallic liner sheet member 30, to create a rigid,integral, composite material lid 20 which has improved damage- andfailure-resistance properties. A suitable foam 40 for injection into theinterior cavity 42 is a combination of ISOFOAM R-1322B, a polyurethanepolyol blend containing a surfactant, catalyst, flame retardant andhydrochlorofluorocarbon, and ISOFOAM I-0732A, a polyurethane isocyanate,sold by IPI International, Inc., which upon reaction forms a foam ofrelatively high density which adheres to the aluminum members and curesinto a rigid body.

Between the multiple stitch welds 99 are corresponding weld gaps 36through which air and gases incident to the foam expansion process canescape through the gas permeable non-welded portions of theliner-to-top-sheet-member edge junction at the periphery of the innerliner member 30 that facilitates comprehensive migration of the foamtoward the edges of the inner liner member 30 thereby defining afunneled, gas permeable apex boundary. This gas exhaust capability isusefully employed in the parallel plane boundary of the internal cavity42 in which upon injection of the liquid foam, pockets of air and othergases may become sealed off by the expanding foam from otherwiseavailable vent holes through the surface of liner sheet member 30. Theparallel plane internal contour of the internal cavity 42 ensures thatgasses that are not exhausted through the injection or ventilation portsin the surface of the inner sheet member 30 are directed toward theoutermost apex boundary of the internal cavity 42 where the wedgedcontour of the liner-sheet-to-beveled-edge boundary creates a nozzleeffect that facilitates expulsion of the gasses through the weld gaps36. Furthermore, although gas permeable, the non-welded contactjunctions at weld gaps 36 between the edges of the inner liner 30 andthe beveled portions of the top sheet edges 22, 23 and 24 provides asignificant degree of resistance to foam expansion to prevent excessivefoam expansion through the weld gaps 36 sufficient to account for anyincidental process variations of a timed or metered foam injectionprocess.

An alternative truck bed toolbox lid 25 is depicted in FIG. 4, wherein ahot glue seal 34, referred to alternatively as a hot melt seal, isdisposed along the gaps of the outer perimeter of the metallic linersheet member 30, such that upon cooling the hot glue sealing memberforms a continuous seal between the inside surface of the top sheetmember 21 and the outer edge perimeter of the liner sheet member 30. Asexplained in further detail with reference to FIG. 6, hot glue seal 34is applied during assembly of the truck bed toolbox lid prior toinjection of the foam into the internal cavity 42. Hot glue seal 34retains the foam 40 within a defined area and prevents the foam 40 fromexpanding through the weld gaps 36 between the stitch welds 99.

It has been found that the presence of the cured foam 40 in the interiorcavity 42 bonding the upper sheet member 21 to the metallic liner sheetmember 30 is a much stronger construction than that of the previouslyknown constructions, enabling thinner metal sheets to be utilized in theconstruction of the lids 20 and obviating the need for interior bracingmembers, which lowers material costs yet still provides improvedproperties over standard constructions. For example, a suitable lid 20is formed with a one half to three quarter inches in depth cavity 42between a liner sheet member 30 of only 0.050 mil metallic sheetthickness and a top sheet member 21 of only 0.063 mil metallic sheetthickness.

Referring to FIG. 6, there is depicted a flow diagram illustrating stepsperformed during production of a truck bed toolbox lid in accordancewith a preferred embodiment of the present invention. The process beginsas shown at step 52 and proceeds to steps 54 and 56 with the inner sheetliner 30 being placed on and stitch welded to the beveled edge perimeter33. Next, as depicted at step 58, hot glue seal 34 is applied along thestitch welded perimeter. In accordance with one embodiment, the seal isapplied using a glue gun (not depicted) consisting of a handle, anelectrically heated, thermostatically controlled melting chamber and anapplication nozzle. The hemmed liner edges 31 form a provide a suitablydimensioned trough or “well” in which the heat-activated adhesive can bedeposited after stitch welding. It should be noted that the hot glueapplication step 58 is optional and that the truck bed toolbox lid 20may be produced as previously discussed without utilizing the hot glueseal 34.

Following application of hot glue seal 34, the truck bed toolbox lid 20is placed in a clam-style jig in preparation for the foam injectionprocess. FIG. 5 illustrates an example clam-style jig 45 into which thetruck bed toolbox lid 20 is placed prior to and during the foaminjection process. Cavity support members 44 are provided within theinterior cavity 42 to structurally support the liner sheet member 30prior to the foam injection process. The liner sheet member 30 is bracedby suitable blocks 46 such that it does not flex outward after the foam40 begins to expand. Proceeding to step 61, the foam is injected throughthe injection ports 41 in metered amount under controlled conditionssuch that the interior cavity 42 is filled to capacity upon expansionand curing. As illustrated at step 63, prior to and/or during the foaminjection step, a heater element 48 is situated beneath the braced lidand utilized to heat the metallic sheet members 30 and 21 to control therate at which the injected foam cures and thereby facilitate maximumexpansion and a relatively uniform time at which the expanded foamfinally cures as a rigid member. The injection is terminated (step 69)either automatically, if using a metered or timed foam injection system(steps 64 and 65), or in accordance with an operators inspection andjudgment (steps 64 and 67).

Following the foam injection process, the injection ports 41 are coveredby one or more adhesive members so that the foam 40 does not expandthrough the injection ports 41. The lid 20 is left in the jig forsufficient time such that the vast majority of the expansion hasoccurred, and the lid 20 is then removed from the jig and allowed tofully cure. With this structure, the lid 20 can be further processed,such as by powder coating, painting or the like to produce aestheticimprovements, some of which processes require high temperatureenvironments detrimental to the foam 40, with the foam 40 later injectedinto the interior cavity 42 to increase structural rigidity andstiffness.

Tests on lids 20 constructed as described versus standard lids or lidswith inserted pre-cured, cut-to-size, foam panels show remarkableimprovements relative to desired stiffness characteristics. In a firsttest apparatus, lids were clamped or secured along one end to ahorizontal platform such that approximately half the lid extended beyondthe edge of the platform. Pressure was applied using a hydraulic jack tothe free end of the lid adjacent the free lateral edge member 23 at themidpoint or center. Pressure was applied until the lid failed, withfailure defined to be crimped edges with the lid taking on a permanentlydeformed set. The lid 20 of the invention was able to withstand up to480 psi of vertical pressure prior to failure, while the standard lidconstruction failed at 250 psi and the insert construction failed at 360psi. In addition, the standard lid construction failed at only 1.25inches of deflection, the insert construction failed at only 4 inches ofdeflection, while the lid 20 of the invention did not fail untildeflected 6.25 inches. In other words, the lid 20 of the invention couldbe flexed slightly less than 6.25 inches at 480 psi and would resume itspre-test shape without any permanent deformation.

In a second test, the pressure was applied to one corner of the free endof the lids to introduce torque. For the torque load tests, theinvention withstood up to 490 psi without failure, while the standardlid failed at 280 psi and the insert lid failed at 310 psi. The standardlid failed at only 1.25 inches of deflection and the insert constructionfailed at only 5 inches of deflection. The lid 20 of the invention didnot fail even at deflection of almost 7.5 inches under the failuredefinition set forth above.

It is contemplated that equivalents and substitutions to certainelements set forth above may be obvious to those skilled in the art, andthus the true scope and definition of the invention is to be as setforth in the following claims.

1. A method for producing a truck bed toolbox lid comprising: providinga metallic top sheet member having a depending front edge member, adepending rear edge member and depending lateral edge members, whereinan edge perimeter is formed along the depending front, rear and lateraledge members; providing a substantially flat metallic liner sheetmember; joining said metallic liner sheet member to said metallic topsheet member in edge contact abutment with said edge perimeter so as todefine an internal cavity having a funneled, gas permeable apexboundary; and injecting a self-expanding, self-curing foam into saidinternal cavity in an amount such that said internal cavity iscompletely filled upon expansion of said foam, wherein said foam expandstoward said funneled, gas permeable apex boundary and cures, such thatsaid foam adheres to said metallic top sheet member and said metallicliner sheet member, and such that said metallic top sheet member, saidfoam and said metallic liner sheet member form a rigid composite member.2. The method of claim 1, further comprising applying a hot meltadhesive sealing member along the perimeter of said liner sheet member,such that upon cooling said hot melt adhesive sealing member forms aseal between the inside surface of said top sheet member and the outeredge perimeter of said liner sheet member to retain said foam withinsaid internal cavity.
 3. The method of claim 1, further comprisingheating said metallic top sheet member and said metallic liner sheetmember during said injecting step.
 4. The method of claim 1, whereinsaid edge perimeter is beveled.
 5. The method of claim 1, wherein saidjoining step is performed by stitch welding said metallic liner sheetmember to said beveled edge perimeter.
 6. The method of claim 1, whereinsaid joining step is performed by disposing said liner sheet generallyparallel to said metallic top sheet member.
 7. The method of claim 1,wherein said metallic top sheet member is produced by cutting, foldingand welding a single sheet of aluminum.
 8. A method for producing atruck bed toolbox lid comprising: providing a metallic top sheet memberhaving a depending front edge member, a depending rear edge member anddepending lateral edge members; providing a metallic liner sheet member;joining said metallic liner sheet member to said metallic top sheetmember to define an internal cavity; and injecting a self-expanding,self-curing foam into said internal cavity such that said foam adheresto said metallic top sheet member and said metallic liner sheet member,and such that said metallic top sheet member, said foam and saidmetallic liner sheet member form a rigid composite member upon curing ofsaid foam.
 9. The method of claim 8, further comprising the step ofsizing said metallic liner sheet member such that it is substantiallycoextensive with said metallic top sheet member.
 10. The method of claim9, further comprising the step of configuring said metallic liner sheetmember such that it is planar.
 11. The method of claim 10, wherein saidjoining step comprises disposing said metallic liner sheet memberparallel to said metallic top sheet member.
 12. The method of claim 8,further comprising the step of bracing said metallic liner sheet memberprior to said injecting step, such that said metallic liner sheet memberis prevented from flexing outward after injection of said foam.
 13. Themethod of claim 8, further comprising the step of heating said metallicliner sheet member and said metallic top sheet member prior to saidinjecting step.
 14. The method of claim 8, further comprising the stepof heating said metallic liner sheet member and said metallic top sheetmember during said injecting step.
 15. A method for producing a truckbed toolbox lid comprising: providing a metallic top sheet member havinga depending front edge member, a depending rear edge member anddepending lateral edge members; providing a metallic liner sheet member;joining said metallic liner sheet member to said metallic top sheetmember to define an internal cavity; and injecting a self-expanding,self-curing foam into said internal cavity such that said foam adheresto said metallic top sheet member and said metallic liner sheet member,and such that upon curing of said foam the rigidity of the combinationof said metallic top sheet member and said metallic liner sheet memberis increased.
 16. The method of claim 15, further comprising the step ofsizing said metallic liner sheet member such that it is substantiallycoextensive with said metallic top sheet member.
 17. The method of claim16, further comprising the step of configuring said metallic liner sheetmember such that it is planar.
 18. The method of claim 17, wherein saidjoining step comprises disposing said metallic liner sheet memberparallel to said metallic top sheet member.
 19. The method of claim 15,further comprising the step of bracing said metallic liner sheet memberprior to said infecting step, such that said metallic liner sheet memberis prevented from flexing outward after injection of said foam.
 20. Themethod of claim 15, further comprising the step of heating said metallicliner sheet member and said metallic top sheet member.
 21. A method forproducing a truck bed toolbox lid comprising: providing a metallic topsheet member having depending edge members; providing a substantiallyflat metallic liner sheet member; joining said metallic liner sheetmember to said metallic top sheet member in a manner which defines acavity therebetween; and injecting foam-forming material into saidcavity such that foam formed thereby adheres to said metallic top sheetmember and said metallic liner sheet member so as to form a strengthenedcomposite member.
 22. The method of claim 21, wherein sufficientfoam-forming material is injected into said cavity such that the finalproduct lid can be deflected in excess of four inches while remaininguncrimped, with no permanent set, when said lid is secured on ahorizontal platform with approximately half the length of said lidextending beyond said platform and said lid is subjected to centerpressure adjacent one of said depending edge members.
 23. The method ofclaim 21, wherein sufficient foam-forming material is injected into saidcavity such that the final product lid can be deflected to 7.5 incheswhile remaining uncrimped, with no permanent set, when said lid issecured on a horizontal platform with approximately half the length ofsaid lid extending beyond said platform and said lid is subjected tocorner pressure adjacent one of said depending edge members.
 24. Amethod for producing a truck bed toolbox comprising: forming a lid bysteps including providing a metallic top sheet member having dependingedge members; providing a substantially flat metallic liner sheetmember; joining said metallic liner sheet member to said metallic topsheet member in a manner which defines a cavity therebetween; andinjecting foam-forming material into said cavity such that foam formedthereby adheres to said metallic top sheet member and said metallicliner sheet member so as to form a strengthened composite member;providing a generally rectangular, generally tub-shaped, open-toppedlower receptacle; joining the lid to the lower receptacle in a mannerwhich permits the lid to pivot upwardly to expose the interior of thelower receptacle.
 25. The method of claim 24, wherein sufficientfoam-forming material is injected into said cavity such that the lid canbe deflected in excess of four inches while remaining uncrimped, with nopermanent set, when said lid, before being joined to the lowerreceptacle, is secured on a horizontal platform with approximately halfthe length of said lid extending beyond said platform and said lid issubjected to center pressure adjacent one of said depending edgemembers.
 26. The method of claim 24, wherein sufficient foam-formingmaterial is injected into said cavity such that the lid can be deflectedto 7.5 inches while remaining uncrimped, with no permanent set, whensaid lid, before being joined to the lower receptacle, is secured on ahorizontal platform with approximately half the length of said lidextending beyond said platform and said lid is subjected to cornerpressure adjacent one of said depending edge members.
 27. The method ofclaim 24, wherein said metallic liner sheet member is joined to saidmetallic top sheet member at a plurality of discrete locations with gapstherebetween through which gas can escape.
 28. The method of claim 27,wherein said metallic liner sheet member is joined to said metallic topsheet member by welding.
 29. The method of claim 28, wherein saidmetallic liner sheet member is joined to said metallic top sheet memberby stitch welding.
 30. The method of claim 24, wherein the metallic topsheet member is 0.063 inch thick.